Premises and Equipment (Major Classifications) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,859,822	$ 1,810,954
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	726,778	675,125
Property, Plant and Equipment, Net	1,133,044	1,135,829
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	285,612	279,932
Premises and leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,130,650	1,089,644
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 443,560	$ 441,378